Assessment of the In Vivo and In Vitro Release of Chemical Compounds from Vespa velutina

Abstract

Vespa velutina has been rapidly expanding throughout Galicia since 2012. It is causing human health risks and well-known losses in the beekeeping sector. Control methods are scarce, unspecific, and ineffective. Semiochemicals are insect-derived chemicals that play a role in communication and they could be used an integrated pest management tool alternative to conventional pesticides. A previous determination of the organic chemical profile should be the first step in the study of these semiochemicals. HS-SPME in living individuals and the sting apparatus extraction followed by GC-MS spectrometry were combined to extract a possible profile of these compounds in 43 hornets from Galicia. The identified compounds were hydrocarbons, ketones, terpenes, and fatty acid, and fatty acid esters. Nonanal aldehyde appeared in important concentrations in living individuals. While pentadecane, 8-hexyl- and ethyl oleate were mainly extracted from the venom apparatus. Ketones 2-nonanone, 2-undecanone and 7-nonen-2-one, 4,8-dimethyl- were identified by both procedures, as was 1,7-Nonadiene, 4,8-dimethyl-. Some compounds were detected for the first time in V. velutina such as naphthalene, 1,6-dimethyl-4-(1-methylethyl). The chemical profile by caste was also characterized.

Chemical profiles of venom glands in queens, foundresses, pre-wintering gynes, and workers in the hornet Vespa velutina nigrithorax

“…Finally, work on an invasive population in Spain observed 8 compounds [26], collected in vivo by SPME from seven hornets, including 3 previously seen ketones [27,42,43]. However, in this most recent study, individuals displayed marked diversity in their chemical profiles since 2 of the 8 compounds were found in only one hornet and 3 others in fewer than 3 hornets [26]; only one compound occurred across all the profiles. There is clearly a need for further research given this range of results.…”

“…However, others had never been reported before, including 4 unknown acetates of aliphatic alcohols and citronellyl acetate, which had the second highest abundance [27]. Finally, work on an invasive population in Spain observed 8 compounds [26], collected in vivo by SPME from seven hornets, including 3 previously seen ketones [27,42,43]. However, in this most recent study, individuals displayed marked diversity in their chemical profiles since 2 of the 8 compounds were found in only one hornet and 3 others in fewer than 3 hornets [26]; only one compound occurred across all the profiles.…”

“…Peaks present in both V. v. auraria [42] and V. v. nigrithorax [43]. Peaks present in V. v. nigrithorax populations in Italy [27] and Spain [26]. All the compounds observed in this study (a to z) underwent MS analysis (•) and were identified by comparing their mass spectra with those in the NIST 2017 database (ε) and/or in the literature ( ); final validation was performed using available standards (∆).…”

“…The third unknown compound (s, Table 2, Figure 3A) was thought to be 4,8-dimethyl-1,7nonadiene (Figure 3B, Table 1). Indeed, this compound was identified [26] based on the HS-SPME chromatogram. However, its MS spectra, retention time, and KRI value differed from those of the 4,8dimethyl-1,7-nonadiene standard (Figure 3).…”

“…Furthermore, because they lack specificity, these traps can have significant ecological impacts on a wide range of non-target species [22,23]. As a result, work is currently underway [20] to develop new species-specific systems that are based on pheromones [24][25][26][27].…”